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PubMed1995

[Evaluation of segregation ratio and hereditability of esophageal cancer--a comparative epidemiologic study in Huai'an County].

A genetic epidemiologic case-control study including 407 pedigrees (249 cases and 158 controls) was carried out to estimate the segregation ratio and the hereditability (h2) of esophageal cancer by using the method of Li-Mantel-Gart and Falconer, respectively, and to compare the genetic epidemiologic features from the other cancers. The results showed that the segregation ratio of esophageal cancer was 0.1347, significantly less than 0.25 and the genetic model belonged to polygenetics. The h2 of esophageal cancer was 21.41%, 20.23% for female and 13.57% for male. It is concluded that genetic factor is one of the risk factors for esophageal cancer and specially of importance for female, but it is not a main risk factor for esophageal cancer. The results of comparative epidemiologic study among the cancers of lung, stomach, liver and large bowel showed that the segregation ratios of the cancers (except stomach, no data) were all less than 0.25, and the h2 of gastric and liver cancers were higher, which were 52.40% and 51.85%, respectively.

Case-Control Studies↗
PubMed1994

Testing for segregation distortion in the HLA complex.

One of the long-standing issues in HLA research is whether there is segregation distortion in the HLA complex in human populations. In this paper we study some simple statistical models aimed at detecting segregation distortion. We present a statistic to test the Mendelian null hypothesis of equal transmission probabilities. To assess the possible contribution of multiple alleles to segregation distortion, we employ a specific log-linear model for transmission probabilities equivalent to the Bradley-Terry model in the literature of paired comparisons. We also provide a simple method for detecting a single allele effect, if present.

Alleles↗
PubMed1993

[Autoradiographic and biochemical studies of protein synthesis in nucleated erythrocytes during the formation of their segregation apparatus].

It has been shown that during novocaine (4.6 x 10(-3) M) induced formation of the segregation apparatus (SA) the total protein synthesis decreases, the synthesis of certain proteins being characterized by a high rate turnover. In the intact erythrocytes, 1 x 10(-2) cycloheximide (CHM) inhibits the novocaine induced formation of segregation apparatus (SA) and protein synthesis by 90%. The combined action of novocaine and CHM on erythrocytes is accompanied by a decrease in CHM inhibiting effect on protein synthesis. This effect retains for 1.5 h during the action of both compounds. Some vacuoles of SA disposed cytochemically exposed acid phosphatase (AP), which enabled us to consider these as lysosomes. According to AP distribution in lysosomes, they can be classified into 3 groups. In group 1 AP is distributed along the membrane of vacuoles, in group 2 it is associated with the material inside the lysosome, and in group 3 the enzyme is both distributed along the membrane and associated with the material enclosed within the segregation vacuole. Such a mode of AP distribution reflects presumably the functional heterogeneity of lysosomes.

Acid Phosphatase↗
PubMed1995

Segregation and convergence of specialised pathways in macaque monkey visual cortex.

At the level of cortical area V2, the various visual inputs to the cortex have reorganised to form 3 distinct channels. Anatomically these are embodied in the thick and thin dark stripes, and paler interstripes characteristic of cytochrome oxidase architecture. Do the outputs of these compartments remain segregated at higher levels of processing, or are they in turn combined and repackaged? To examine this question we have injected distinct orthograde tracers into the functionally distinct areas V4 and V5 of one hemisphere in 3 macaque monkeys (Macaca fascicularis). V4 is known to receive input from both thin stripes and interstripes of V2, but some parts of V4 receive only interstripe afferents, others receive a relatively greater contribution from the thin stripes. Thus V4 itself is thought to possess subcompartments of at least two distinct types, acting to extend the blob-thin stripe and interblob-interstripe pathways through V1 and V2. The experiments reported here reveal no further divergence between these channels: both types of V4 subcompartment make rather similar patterns of connection with further visual areas and subcortical structures. In contrast to V4, area V5 receives input from the thick stripes of V2. V4 and V5 are weakly interconnected, at best, and there is limited direct convergence in their two sets of ascending connections. For instance, both areas send output to area LIP; but V4 targets the dorsal half of the area, and V5 the ventral half, with some minor overlap. Projections to the superior temporal sulcus are also mainly separate, although we found instances of direct convergence in areas FST and possibly V4t. Segregation is also the rule for subcortical connections to the pulvinar from these two areas. In summary, the segregated outputs of V2 can remain largely distinct through at least two subsequent stages of cortical processing.

Animals↗
PubMed1996

Mutation segregation and rapid carrier detection of X-linked muscular dystrophy in dogs.

OBJECTIVES: To use exon 7-specific genomic polymerase chain reaction (PCR) products to identify the genotypes of normal, affected, and carrier female dogs in pedigrees segregating Golden Retriever muscular dystrophy (GRMD), and to confirm the concordant segregation of the mutation in all carrier and affected dogs presently available. DESIGN: The GRMD mutation is found in the consensus splice acceptor site in intron 6 of the canine dystrophin gene. PCR cycle-sequencing and restriction fragment length polymorphism/PCR were used for determination of the pattern of segregation of the point mutation which causes GRMD. ANIMALS: Normal, clinically affected, and obligate carrier dogs in pedigrees of GRMD. PROCEDURE: DNA from blood was amplified, using PCR and primers that bracket all of exon 7 of the canine dystrophin gene as well as 100 base pairs of intron on either side. PCR products were either cycle-sequenced directly or submitted to a second round of PCR, using 1 of the original primers coupled with a mutagenic restriction fragment length polymorphism-primer, which thus creates an artificial restriction site. Digestion with Stu I detected the normal allele. To detect the affected allele, Sau96 I was used to digest the 310-base pair exon 7 genomic fragment directly. CONCLUSIONS: Simple, clear diagnosis of carrier status was possible using these methods. This mutation is passed through all carrier and affected dogs in both United States GRMD colonies and the colony in Australia. CLINICAL RELEVANCE: Rapid, accurate diagnosis of carrier and affected dogs will enhance study of this homologue of Duchenne muscular dystrophy.

Alleles↗
PubMed1996

Population biology of human aging: segregation analysis of bone age characteristics.

The main goal of the present study is to elucidate the extent to which primary characteristics of bone aging are determined by major gene effects. We report the results of a complex segregation analysis of bone mineral density (BMD) and osseographic score (OS) carried out on an array of pedigrees from rural Turkmenia. Both variables showed a significant correlation with age and thus were adjusted. However, the correlations with body height, weight, body mass index, and obesity indexes were negligible. The results of the segregation analysis performed on BMD clearly indicate major gene effects on BMD variation. The Mendelian transmissibility hypothesis with two codominant alleles was chosen as the best-fitting and most parsimonious model. Under this hypothesis 50-60% of total variation in BMD, depending on bone area, can be attributed to a major gene effect, and the frequency of the allele determining the higher value of bone density is between 30% and 38% in the Turkmenian population. Regarding the OS, segregation analysis provided evidence supporting intergenerational transmissibility of this characteristic and yet the Mendelian model was rejected.

Adolescent↗
PubMed1996

[Department social climate on mixed sex and segregated acute psychiatric units. Results of a survey].

The segregation of sexes in an acute psychiatric unit was followed up by means of a research survey. Patients and staff members were questioned about the ward climate before and after changing the admission procedure. The male patients merely noticed a decreased influence of sexual problems on the ward atmosphere. The female patients evaluated the new ward for women as an improvement. In particular, assistance and clarity of conditions were more positively assessed. The staff members of the previous open ward noticed a significant increase in annoyance and aggression after closing the ward and segregation of the sexes. In general, segregation of the sexes did not result in deterioration of the ward atmosphere.

Adaptation, Psychological↗
PubMed1977

Segregation analysis of thalassemia in Ferrara.

Segregation analysis of 996 families in which the gene for beta-thalassemia was segregating showed no distortion of expected Mendelian ratios. No appreciable frequency of sporadic cases was detected. It was suggested that segregation distortion is not a mechanism which contributes to the maintenance of polymorphism in the beta-thalassemia system in the population of the Ferrara area.

Computers↗
PubMed1998

Segregation analysis reveals a major gene effect controlling systolic blood pressure and BMI in an Israeli population.

It has been suggested that genetic factors control blood pressure level at all ages. However, the evidence is limited because of the composite nature of blood pressure and the heterogeneity of the studied samples. The purpose of the present study is to test for genetic influences on systolic blood pressure (SBP) level in a community-based Israeli family study. Segregation analysis was performed on 622 adults from 208 pedigrees. Age, sex, and body mass index (BMI) were significant covariates of SBP. Segregation analysis rejected the environmental transmission model but not the mixed Mendelian transmission model. The best-fitting genetic model was the mixed codominant model, with a heritability of 0.32 and an allele frequency of 0.18 for high SBP level. We further tested whether SBP and BMI shared a common major gene effect. Using bivariate segregation analysis involving two traits and a single locus, we found evidence for a single-locus pleiotropic effect on SBP and BMI. The allele frequency of this major locus was 0.24. The residual genetic correlation resulting from additive polygenes and the environmental correlation between these two traits were not different from zero after taking into account the shared major gene effect. The proportion of phenotypic variation attributable to this major gene effect increased with age for SBP but decreased with age for BMI.

Adult↗
PubMed1998

Analysis of meiotic segregation in human nondecondensed interphase spermatozoa by triple colour rapid direct fluorescent in situ hybridization.

Meiotic segregation of chromosomes X,Y and 1 was analyzed by triple colour rapid fluorescent in situ hybridization (FISH) with directly labelled probes on 4506 non-decondensed and non-cleaned interphase spermatozoa from four healthy male donors to test the possibility of rapid sperm FISH by omitting the conventional sperm decondensation and cleaning steps. Only 0.15 per cent of sperms were without any signals which suggested high hybridization success. An abnormal number of signals was seen in 1.6 per cent of sperms. Chromosome specific as well as donor specific segregation error was seen similar to previous reports. There was a wide variation in the ratio of normal X and Y bearing sperm from donor to donor. This study indicated that for segregation studies sperm FISH can be carried out in three hours with directly labelled probes without the steps for separation of sperm from somatic cells (cleaning), sperm swelling and sperm DNA decondensation.

Humans↗
PubMed1998

The influence of sexual dimorphism in body size and mouth morphology on diet selection and sexual segregation in cervids.

In mammals patterns of food resource distribution influence female distribution, leading to aggregation and favouring the evolution of a polygynous mating system. Under polygyny, sexual selection favours an increase of the male body size, since larger bodied males have competitive advantage in fights for mates. As a result, sexual body size dimorphism is a general rule in polygynous artiodactyls and is correlated with the degree of polygyny. Sex differences in body size lead to differences in energy requirements and food selection between the sexes. This has led to the sexual size dimorphism hypothesis being used to explain sexual segregation in ungulates, although from the available studies, it is not possible to deduce a consistent pattern between sexes in the use of forage of different abundance or quality. Two other groups of hypotheses have been put forward to explain sexual segregation in ungulates. These are based on reproductive strategy and social factors, both of which are independent of body size. The mechanistic explanation for differences in food selection ability and intake rate between animals of different body size and how this can lead to an understanding of the sex differences in diet and sexual segregation, both of which are intimately linked, is discussed.

Animal Nutritional Physiological Phenomena↗
PubMed1999

Prenatal development of retinogeniculate axons in the macaque monkey during segregation of binocular inputs.

In the fetal monkey the projections from the two eyes are initially completely intermingled within the dorsal lateral geniculate nucleus (DLGN) before separating into eye-specific layers (). To assess the cellular basis of this developmental process, we examined the morphological properties of individual retinogeniculate axons in prenatal monkeys of known gestational ages. The period studied spanned the time from when binocular overlap has been reported to be maximum, circa embryonic (E) day 77 through E112, when the segregation process is already largely completed in the caudal portion of the nucleus. Retinogeniculate fibers were labeled by making small deposits of DiI crystals into the fixed optic tract. After adequate time was allowed for diffusion of the tracer, fibers were visualized by confocal microscopy, and morphometric measures were made from photomontages. This revealed that retinogeniculate fibers in the embryonic monkey undergo continuous growth and elaboration during binocular overlap and subsequent segregation. Importantly, very few side-branches were found along the preterminal axon throughout the developmental period studied. Thus, restructuring of retinogeniculate fibers does not underlie the formation of eye-restricted projections in the primate. Rather, the results support the hypothesis that binocular segregation in the embryonic monkey is caused by the loss of retinal fibers that initially innervate inappropriate territories ().

Animals↗
PubMed2005

Deletion of and novel missense mutation in POU3F4 in 2 families segregating X-linked nonsyndromic deafness.

OBJECTIVE: To analyze the physical manifestations and genetic features of 2 families segregating X-linked deafness, which is most commonly reported to be caused by mutations of the POU domain gene POU3F4 at the DFN3 locus. DESIGN: Computed tomographic study of the temporal bone in probands from each family, followed by mutation screening and deletion mapping of POU3F4 in family members. SETTING: Two midwestern genetics clinics. PARTICIPANTS: Two families with X-linked deafness. MAIN OUTCOME MEASURES: Anomalies of the inner ear in the probands; results of gene mapping and severity and effects of hearing loss in the family members. RESULTS: In the first family, a large deletion was identified that includes POU3F4 and extends upstream approximately 530 kilobases; in the second family, a novel serine-to-leucine (S228L) amino acid mutation was identified in the POU-specific domain of POU3F4. Both the deletion and the missense mutation segregate with the clinical phenotype and are causally related to the deafness in these families. CONCLUSIONS: Deafness related to the POU3F4 gene is associated with dilation of the internal auditory canal and a spectrum of other temporal bone anomalies that range in severity from mild to severe dysplasia of the cochlea and semicircular canals. The consequence of these anomalies is a congenital mixed hearing loss, the sensorineural component of which progresses over time. Affected males can also present with vestibular dysfunction that is associated with delayed developmental motor milestones. Intrafamilial variability occurs.

Chromosome Deletion↗
PubMed1999

Segregation analysis of obsessive-compulsive disorder using symptom-based factor scores.

Obsessive-compulsive disorder (OCD) is a complex psychiatric disorder characterized by recurring obsessions or compulsions that cause significant distress to the patient or significantly interfere with the patient's normal home, work, or social activities [Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. Washington, DC: American Psychiatric Association, 1994]. Twin and family studies have suggested that OCD has a significant genetic component. We performed complex segregation analyses using POINTER with families ascertained through an OCD-affected proband. In an attempt to resolve the phenotypic heterogeneity observed among individuals with OCD these segregation analyses used four factor-analytic symptom dimensions to subset the family sample based upon probands' symptom factor scores. Analysis of the entire sample allowed rejection of only the no transmission model; that model was also rejected in all subsequent analyses. Limiting the analyses to families with at least one OCD-affected member in addition to the proband (the demonstrably familial form of OCD) allowed rejection of all models except the mixed model. Analyses limited to families of high-factor-3 (symmetry and ordering symptoms) probands led to rejection of the polygenic model, indicating the involvement of a major locus. Additionally, the relative risk of OCD or subclinical OCD was 1.7 for relatives of probands with a factor 3 score greater than zero compared with relatives of probands with a low factor score. The symptoms attributed to high factor 3 scores (symmetry and ordering) may constitute a genetically significant symptomatic subtype of OCD. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:669-675, 1999.

Aging↗
PubMed1999

Segregation analysis of the specific response to allergens: a recessive major gene controls the specific IgE response to Timothy grass pollen.

Segregation analysis of the specific response to allergens (SRA) was performed in a sample of 234 randomly selected Australian families using the regressive models. Various SRA phenotypes were considered using broad and narrow definitions of these phenotypes, according to the type of test used, skin test or RAST test, and the specificity of the response to allergen. Strong evidence for familial dependencies among blood relatives was shown for most SRA phenotypes, especially when using a broad definition. There was no evidence for a Mendelian factor accounting for the familial transmission of these broadest phenotypes, which may involve multiple factors preventing the clear detection of a major effect with Mendelian transmission. However, segregation of a Mendelian recessive major gene was detected for one SRA sub-phenotype, the IgE response to a single allergen, Timothy grass pollen, measured by the RAST test. Identification of a specific SRA phenotype controlled by a major gene may have important implications for further linkage studies.

Adolescent↗
PubMed2006

A microdeletion in Xp11.3 accounts for co-segregation of retinitis pigmentosa and mental retardation in a large kindred.

In a previous report, Aldred et al. [1994] described a 5-generation family in which severe retinitis pigmentosa (RP) co-segregates with mild-moderate mental retardation as an X-linked recessive phenotype mapping to the broad interval between Xp21-q21. We re-examined this family, initially analyzing RP2, a gene in the disease interval that was identified as a cause of RP after the initial report of this family. We found that the male propositus lacked the 5' three exons of RP2 and that RP2 marks the centromeric boundary of a 1.27 Mb deletion that includes two other annotated genes (SLC9A7, CHST7), one predicted transcript encoding a zinc finger protein (FLJ20344) and two highly conserved miRNAs (mir221, mir222). We conclude that this family is segregating a contiguous gene deletion and that the absence of a functional RP2 accounts, at least in part, for the retinal degeneration while deletion of one or more of the other genes is likely responsible for the mental retardation phenotype.

Antiporters↗
PubMed1984

Genetic Analysis Workshop II: results of segregation analyses using POINTER and linkage analyses using LIPED.

Genetic Analysis Workshop II Problems 2 and 3 were analyzed using the segregation analysis program, POINTER and the linkage analysis program LIPED. Results of the segregation analyses were acceptable with respect to both parameter estimation and hypothesis testing. Results of the linkage analyses were also good. Although it was noted that the linkage and population association data were sometimes compatible with more than one hypothesis, the correct relationships among the trait and marker loci were generally among those found compatible with the data.

Alleles↗
PubMed1999

Toxic mutations in the recA gene of E. coli prevent proper chromosome segregation.

The recA gene of Escherichia coli is the prototype of the recA/RAD51/DMC1/uvsX gene family of strand transferases involved in genetic recombination. In order to find mutations in the recA gene important in catalytic turnover, a genetic screen was conducted for dominant lethal mutants. Eight single amino acid substitution mutants were found to prevent proper chromosome segregation and to kill cells in the presence or absence of an inducible SOS system. All mutants catalyzed some level of recombination and constitutively stimulated LexA cleavage. The mutations occur at the monomer-monomer interface of the RecA polymer or at residues important in ATP hydrolysis, implicating these residues in catalytic turnover. Based on an analysis of the E96D mutant, a model is presented in which slow RecA-DNA dissociation prevents chromosome segregation, engendering lexA-independent, lethal filamentation of cells.

Adenosine Triphosphate↗